/*
* MathVid interactive-question + lesson-page styles.
*/

:root {
    --mvi-font-body: "myriad-pro", sans-serif;
    --mvi-font-headline: "factoria", sans-serif;
    --mvi-fg: #000000;
    --mvi-bg: #ffffff;
    --mvi-muted: #707271;
    --mvi-border: #b5b6b6;
    --mvi-accent: #be0000;
    --mvi-accent-fg: #ffffff;
    --mvi-focus: #be0000;
    --mvi-part-not-started: #707271;
    --mvi-part-current: #be0000;
    --mvi-part-complete: #000000;
    --mvi-correct-fg: #000000;
    --mvi-correct-border: #6cc24a;
    --mvi-correct-bg: color-mix(
        in srgb,
        var(--mvi-correct-border) 22%,
        #ffffff
    );
    --mvi-incorrect-fg: #000000;
    --mvi-incorrect-bg: #e2e6e6;
    --mvi-incorrect-border: #707271;
    --mvi-neutral-fg: #000000;
    --mvi-neutral-bg: #e2e6e6;
    --mvi-neutral-border: #707271;
    --mvi-radius: 0.5rem;
    --mvi-space: 1rem;
    --mvi-target: 2.75rem; /* ~44px minimum interactive target */
}

/* ---- Page layout (lesson template) ---- */

.mvi-body {
    margin: 0;
    color: var(--mvi-fg);
    background: var(--mvi-bg);
    font-family: var(--mvi-font-body);
    font-size: 1.0625rem;
    line-height: 1.6;
}

.mvi-body h1,
.mvi-body h2,
.mvi-body h3,
.mvi-question-heading {
    font-family: var(--mvi-font-headline);
    font-weight: 700;
}

.mvi-skip-link {
    position: absolute;
    left: 0.5rem;
    top: -3rem;
    z-index: 100;
    padding: 0.5rem 0.75rem;
    background: var(--mvi-accent);
    color: var(--mvi-accent-fg);
    border-radius: var(--mvi-radius);
    transition: top 0.15s ease-in-out;
}

.mvi-skip-link:focus {
    top: 0.5rem;
}

.mvi-container {
    width: 100%;
    max-width: 56rem;
    margin: 0 auto;
    padding: clamp(1rem, 3vw, 2rem);
    box-sizing: border-box;
}

.mvi-course-label {
    margin: 0 0 0.35rem;
    font-size: 0.95rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    color: #555;
}

.mvi-lesson-header h1 {
    font-size: clamp(1.5rem, 4vw, 2.1rem);
    line-height: 1.25;
    margin-top: 0;
    margin-bottom: 0.5rem;
}

.mvi-video {
    margin: var(--mvi-space) 0;
}

.kaltura-video {
    position: relative;
    width: 100%;
    max-width: 832px;
    margin: var(--mvi-space) 0;
    height: 0;
    /* 56.25% of width = 16:9 video area; +60px for Kaltura player controls */
    padding-bottom: calc(56.25% + 60px);
}

.kaltura-video iframe {
    position: absolute;
    top: 0;
    left: 0;
    display: block;
    width: 100%;
    height: 100%;
    border: 0;
}

.mvi-video-placeholder {
    border: 2px dashed var(--mvi-border);
    border-radius: var(--mvi-radius);
    padding: var(--mvi-space);
    color: var(--mvi-muted);
}

.mvi-resources-list {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.mvi-resources-list--primary {
    gap: 1rem;
}

.mvi-resource-card {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    min-height: var(--mvi-target);
    min-width: min(100%, 14rem);
    padding: 0.85rem 1rem;
    border: 1px solid var(--mvi-accent);
    border-radius: var(--mvi-radius);
    color: inherit;
    text-decoration: none;
    background: transparent;
}

.mvi-resource-card:hover {
    background: #fcf8f8;
}

.mvi-resource-card:focus-visible {
    outline: 3px solid var(--mvi-focus);
    outline-offset: 2px;
}

.mvi-resource-title {
    font-weight: 600;
    color: var(--mvi-accent);
}

.mvi-resource-meta {
    font-size: 0.9rem;
    line-height: 1.45;
    color: var(--mvi-muted);
}

.mvi-source-disclosure {
    margin-top: 1.25rem;
    border-top: 1px solid var(--mvi-border);
    padding-top: 0.75rem;
}

.mvi-source-disclosure > summary {
    display: inline-flex;
    align-items: center;
    min-height: var(--mvi-target);
    padding: 0.35rem 0.15rem;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--mvi-muted);
    cursor: pointer;
    list-style: none;
}

.mvi-source-disclosure > summary::-webkit-details-marker {
    display: none;
}

.mvi-source-disclosure > summary::before {
    content: "▸";
    display: inline-block;
    width: 1.1rem;
    margin-right: 0.35rem;
    transition: transform 0.15s ease-in-out;
}

.mvi-source-disclosure[open] > summary::before {
    transform: rotate(90deg);
}

.mvi-source-disclosure > summary:hover {
    color: var(--mvi-fg);
}

.mvi-source-disclosure > summary:focus-visible {
    outline: 3px solid var(--mvi-focus);
    outline-offset: 2px;
    border-radius: var(--mvi-radius);
}

.mvi-source-panel {
    margin-top: 0.75rem;
    max-width: 42rem;
}

.mvi-source-panel p {
    margin: 0 0 0.75rem;
    font-size: 0.9rem;
    line-height: 1.55;
    color: var(--mvi-muted);
}

.mvi-resources-list--source {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.45rem;
}

.mvi-resources-list--source a {
    display: inline-flex;
    align-items: center;
    min-height: var(--mvi-target);
    padding: 0.15rem 0;
    color: var(--mvi-accent);
    text-decoration: underline;
    text-underline-offset: 0.15em;
}

.mvi-resources-list--source a:hover {
    text-decoration-thickness: 2px;
}

.mvi-resources-list--source a:focus-visible {
    outline: 3px solid var(--mvi-focus);
    outline-offset: 2px;
    border-radius: 0.15rem;
}

.mvi-footer {
    color: var(--mvi-muted);
    border-top: 1px solid var(--mvi-border);
    margin-top: 2rem;
    padding-top: 1rem;
    font-size: 0.9375rem;
}

.mvi-footer a {
    color: var(--mvi-accent);
    text-decoration: underline;
    text-underline-offset: 0.15em;
}

.mvi-footer a:hover {
    text-decoration-thickness: 2px;
}

/* ============================================================
    Course lesson outline (subject landing page)
    Chapter cards -> topic cards / solo-lesson cards -> lesson cards
    ============================================================ */

.mvi-outline-intro {
    max-width: 46rem;
    margin: 0 0 1.5rem;
    color: var(--mvi-fg);
}

.mvi-outline {
    --mvi-outline-tint: #fcf8f8;
    --mvi-outline-tint-strong: color-mix(
        in srgb,
        var(--mvi-accent) 9%,
        #ffffff
    );
    margin: 0;
}

.mvi-outline-chapters {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    overflow: visible;
}

.mvi-outline-chapter-item {
    margin: 0;
    overflow: visible;
}

/* ---- Chapter card ---- */

.mvi-outline-chapter {
    border: 1px solid var(--mvi-border);
    border-radius: 0.9rem;
    background: var(--mvi-bg);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.06);
    overflow: hidden;
    transition:
        box-shadow 0.15s ease-in-out,
        border-color 0.15s ease-in-out;
}

.mvi-outline-chapter:hover {
    border-color: color-mix(in srgb, var(--mvi-accent) 35%, var(--mvi-border));
    box-shadow: 0 4px 14px rgba(0, 0, 0, 0.1);
}

.mvi-outline-chapter[open] {
    border-color: color-mix(in srgb, var(--mvi-accent) 30%, var(--mvi-border));
}

.mvi-outline-chapter-summary {
    display: flex;
    align-items: center;
    gap: 0.9rem;
    min-height: var(--mvi-target);
    padding: 1rem 1.15rem;
    cursor: pointer;
    list-style: none;
    user-select: none;
}

.mvi-outline-chapter-summary::-webkit-details-marker {
    display: none;
}

.mvi-outline-chapter[open] .mvi-outline-chapter-summary {
    border-bottom: 1px solid var(--mvi-border);
    background: var(--mvi-outline-tint);
}

.mvi-outline-chapter-summary:hover {
    background: var(--mvi-outline-tint);
}

/* Red chapter-number bubble */
.mvi-outline-chapter-number {
    flex: 0 0 auto;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2.75rem;
    height: 2.75rem;
    border-radius: 50%;
    background: var(--mvi-accent);
    color: var(--mvi-accent-fg);
    font-family: var(--mvi-font-headline);
    font-weight: 700;
    font-size: 1.35rem;
    line-height: 1;
}

.mvi-outline-chapter-text {
    display: flex;
    flex-direction: column;
    gap: 0.1rem;
    flex: 1 1 auto;
    min-width: 0;
}

.mvi-outline-chapter-eyebrow {
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--mvi-muted);
}

.mvi-outline-chapter-label {
    font-family: var(--mvi-font-headline);
    font-weight: 700;
    font-size: 1.3rem;
    line-height: 1.2;
    color: var(--mvi-fg);
}

.mvi-outline-chapter-count {
    font-size: 0.85rem;
    color: var(--mvi-muted);
}

/* ---- Shared chevron (expandable indicator) ---- */

.mvi-outline-chevron {
    flex: 0 0 auto;
    display: inline-block;
    width: 0.7rem;
    height: 0.7rem;
    margin: 0 0.15rem;
    border-right: 2.5px solid currentColor;
    border-bottom: 2.5px solid currentColor;
    transform: rotate(45deg);
    transition: transform 0.15s ease-in-out;
    color: var(--mvi-muted);
}

.mvi-outline-chapter-summary .mvi-outline-chevron {
    color: var(--mvi-accent);
}

.mvi-outline-chapter[open] > .mvi-outline-chapter-summary .mvi-outline-chevron,
.mvi-outline-topic[open] > .mvi-outline-topic-summary .mvi-outline-chevron {
    transform: rotate(225deg);
}

/* ---- Chapter body ---- */

.mvi-outline-chapter-body {
    padding: 0.85rem 1.15rem 1.1rem;
}

.mvi-outline-blocks {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 0.65rem;
}

.mvi-outline-block {
    margin: 0;
    /* Indent topic + solo-lesson cards under the chapter number bubble. */
    margin-left: clamp(0rem, 2vw, 0.85rem);
}

/* ---- Topic card (expandable group) ---- */

.mvi-outline-topic {
    border: 1px solid var(--mvi-border);
    border-radius: 0.6rem;
    background: var(--mvi-bg);
    overflow: hidden;
    transition:
        background 0.15s ease-in-out,
        border-color 0.15s ease-in-out,
        box-shadow 0.15s ease-in-out;
}

.mvi-outline-topic:hover,
.mvi-outline-topic[open] {
    background: var(--mvi-outline-tint);
    border-color: color-mix(in srgb, var(--mvi-accent) 30%, var(--mvi-border));
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.07);
}

.mvi-outline-topic-summary {
    display: flex;
    align-items: center;
    gap: 0.7rem;
    min-height: var(--mvi-target);
    padding: 0.7rem 0.9rem;
    cursor: pointer;
    list-style: none;
    user-select: none;
}

.mvi-outline-topic-summary::-webkit-details-marker {
    display: none;
}

.mvi-outline-topic[open] .mvi-outline-topic-summary {
    border-bottom: 1px solid var(--mvi-border);
    background: var(--mvi-outline-tint);
}

.mvi-outline-topic-summary:hover {
    background: var(--mvi-outline-tint);
}

/* Stacked-cards glyph signals "a group that opens". */
.mvi-outline-topic-icon {
    position: relative;
    flex: 0 0 auto;
    width: 1.35rem;
    height: 1.35rem;
}

.mvi-outline-topic-icon::before,
.mvi-outline-topic-icon::after {
    content: "";
    position: absolute;
    width: 0.85rem;
    height: 0.85rem;
    border: 2px solid var(--mvi-accent);
    border-radius: 0.2rem;
}

.mvi-outline-topic-icon::before {
    top: 0.35rem;
    left: 0.35rem;
    background: var(--mvi-bg);
}

.mvi-outline-topic:hover .mvi-outline-topic-icon::before,
.mvi-outline-topic[open] .mvi-outline-topic-icon::before {
    background: var(--mvi-outline-tint);
}

.mvi-outline-topic-icon::after {
    top: 0;
    left: 0;
    background: var(--mvi-bg);
}

.mvi-outline-topic-text {
    display: flex;
    flex-direction: column;
    gap: 0.05rem;
    flex: 1 1 auto;
    min-width: 0;
}

.mvi-outline-topic-label {
    font-weight: 700;
    font-size: 1.05rem;
    line-height: 1.25;
    color: var(--mvi-fg);
}

.mvi-outline-topic-count {
    font-size: 0.8rem;
    color: var(--mvi-muted);
}

/* ---- "Kind" tag (Topic / Lesson) ---- */

.mvi-outline-kind {
    align-self: flex-start;
    display: inline-block;
    margin-bottom: 0.1rem;
    padding: 0.05rem 0.4rem;
    border-radius: 0.3rem;
    font-size: 0.68rem;
    font-weight: 700;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    line-height: 1.4;
}

.mvi-outline-kind--topic {
    color: var(--mvi-accent);
    background: color-mix(in srgb, var(--mvi-accent) 14%, #ffffff);
}

.mvi-outline-kind--lesson {
    color: var(--mvi-accent-fg);
    background: var(--mvi-accent);
}

/* ---- Lesson cards (solo under a chapter + nested inside a topic) ---- */

.mvi-outline-lesson {
    display: flex;
    align-items: center;
    gap: 0.7rem;
    min-height: var(--mvi-target);
    color: inherit;
    text-decoration: none;
    transition:
        background 0.12s ease-in-out,
        border-color 0.12s ease-in-out,
        box-shadow 0.12s ease-in-out;
}

/* Solo lesson: a card at the same level as topics, but a direct link. */
.mvi-outline-lesson--solo {
    padding: 0.7rem 0.9rem;
    border: 1px solid var(--mvi-border);
    border-left: 4px solid var(--mvi-accent);
    border-radius: 0.6rem;
    background: var(--mvi-bg);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.06);
}

.mvi-outline-lesson--solo:hover {
    background: var(--mvi-outline-tint);
    border-color: color-mix(in srgb, var(--mvi-accent) 30%, var(--mvi-border));
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.07);
}

/* Play glyph reinforces "opens a lesson (video) page". */
.mvi-outline-lesson-icon {
    flex: 0 0 auto;
    width: 0;
    height: 0;
    margin-left: 0.35rem;
    border-top: 0.5rem solid transparent;
    border-bottom: 0.5rem solid transparent;
    border-left: 0.8rem solid var(--mvi-accent);
}

.mvi-outline-lesson-text {
    display: flex;
    flex-direction: column;
    gap: 0.05rem;
    flex: 1 1 auto;
    min-width: 0;
}

.mvi-outline-lesson--solo .mvi-outline-lesson-label {
    font-weight: 700;
    font-size: 1.05rem;
    line-height: 1.25;
}

/* Nested lessons live inside a topic: smaller, further indented. */
.mvi-outline-lessons {
    list-style: none;
    margin: 0;
    padding: 0.6rem 0.9rem 0.75rem;
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
}

.mvi-outline-lessons > li {
    margin: 0;
    margin-left: clamp(0rem, 2vw, 0.75rem);
}

.mvi-outline-lesson--nested {
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--mvi-border);
    border-radius: 0.5rem;
    background: var(--mvi-bg);
    font-size: 0.95rem;
}

.mvi-outline-lesson--nested:hover {
    background: var(--mvi-outline-tint);
    border-color: color-mix(in srgb, var(--mvi-accent) 30%, var(--mvi-border));
}

/* Small numbered bubble gives nested lessons order + distinct look. */
.mvi-outline-lesson-index {
    flex: 0 0 auto;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1.6rem;
    height: 1.6rem;
    border-radius: 50%;
    border: 1.5px solid
        color-mix(in srgb, var(--mvi-accent) 45%, var(--mvi-border));
    background: var(--mvi-bg);
    color: var(--mvi-accent);
    font-weight: 700;
    font-size: 0.85rem;
    line-height: 1;
}

.mvi-outline-lesson-label {
    flex: 1 1 auto;
    min-width: 0;
    color: var(--mvi-fg);
}

.mvi-outline-lesson:hover .mvi-outline-lesson-label {
    text-decoration: underline;
    text-underline-offset: 0.15em;
}

/* Arrow glyph signals a direct link, distinct from the expand chevron. */
.mvi-outline-lesson-go {
    flex: 0 0 auto;
    display: inline-block;
    width: 1.1rem;
    height: 1.1rem;
    color: var(--mvi-accent);
    transition: transform 0.12s ease-in-out;
}

.mvi-outline-lesson-go::before {
    content: "\2192"; /* right arrow */
    font-size: 1.1rem;
    line-height: 1;
}

.mvi-outline-lesson:hover .mvi-outline-lesson-go {
    transform: translateX(0.2rem);
}

/* ---- Focus visibility for outline controls ---- */

.mvi-outline-chapter-summary:focus-visible,
.mvi-outline-topic-summary:focus-visible,
.mvi-outline-lesson:focus-visible {
    outline: 3px solid var(--mvi-focus);
    outline-offset: 2px;
    border-radius: 0.5rem;
}

/* ---- Questions ---- */

.mvi-question {
    border: 1px solid var(--mvi-border);
    border-radius: var(--mvi-radius);
    padding: clamp(0.75rem, 2vw, 1.5rem);
    margin: 1.5rem 0;
}

.mvi-question-heading {
    font-size: 1.3rem;
    margin: 0 0 0.75rem;
}

.mvi-stem {
    margin-bottom: var(--mvi-space);
}

.mvi-text {
    margin: 0 0 0.75rem;
}

.mvi-math {
    margin: 0.5rem 0;
    overflow-x: auto;
}

.mvi-figure {
    margin: 0.75rem 0;
    text-align: center;
}

.mvi-figure-img {
    display: block;
    max-width: 100%;
    height: auto;
    margin: 0 auto;
}

.mvi-parts-accordion {
    margin: 0;
}

.mvi-part {
    border-top: 1px solid var(--mvi-border);
    padding-top: var(--mvi-space);
    margin-top: var(--mvi-space);
}

/* ---- Accordion part headers ---- */

.mvi-part-heading {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.1rem;
    margin: 0;
}

.mvi-part-toggle {
    display: flex;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 0.35rem;
    flex: 1 1 auto;
    min-height: var(--mvi-target); /* WCAG 2.2 target size */
    margin: 0;
    padding: 0.5rem 0.25rem;
    font: inherit;
    font-family: var(--mvi-font-body);
    font-weight: 700;
    text-align: left;
    color: var(--mvi-fg);
    background: transparent;
    border: 0;
    border-radius: var(--mvi-radius);
    cursor: pointer;
}

.mvi-part-label {
    flex: 0 0 auto;
}

/* Chevron rotates with state; decorative, so hidden from assistive tech. */
.mvi-part-toggle::before {
    content: "\25B8"; /* right-pointing triangle */
    flex: 0 0 auto;
    font-size: 0.9em;
    color: var(--mvi-part-not-started);
    transition: transform 0.15s ease-in-out;
}

.mvi-part-toggle[aria-expanded="true"]::before {
    transform: rotate(90deg);
}

/* Future parts: visible and focusable for discoverability, but inert. */
.mvi-part-toggle[aria-disabled="true"] {
    color: var(--mvi-part-not-started);
    cursor: default;
    font-weight: 600;
}

.mvi-part.is-not-started .mvi-part-toggle::before {
    color: var(--mvi-part-not-started);
}

/* State badge. State is conveyed by text (plus a decorative icon), never by
    color alone. */
.mvi-part-status {
    flex: 0 0 auto;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--mvi-part-not-started);
    white-space: nowrap;
}

.mvi-part-status::before {
    margin-right: 0.3rem;
}

.mvi-part.is-not-started .mvi-part-status {
    color: var(--mvi-part-not-started);
}

.mvi-part.is-not-started .mvi-part-status::before {
    content: "\25CB"; /* open circle */
}

.mvi-part.is-current .mvi-part-status {
    color: var(--mvi-part-current);
}

.mvi-part.is-current .mvi-part-toggle::before {
    color: var(--mvi-part-current);
}

.mvi-part.is-current .mvi-part-status::before {
    content: "\25CF"; /* filled circle */
}

.mvi-part.is-complete .mvi-part-status {
    color: var(--mvi-part-complete);
}

.mvi-part.is-complete .mvi-part-toggle::before {
    color: var(--mvi-part-complete);
}

.mvi-part.is-complete .mvi-part-status::before {
    content: "\2713"; /* check mark */
}

.mvi-part-summary {
    flex: 1 1 auto;
    min-width: 0;
    font-weight: 400;
    color: var(--mvi-part-not-started);
    font-size: 0.95rem;
}

.mvi-part.is-complete .mvi-part-summary {
    color: var(--mvi-part-complete);
}

/* Nothing to show until a part is complete, and never for the in-progress
    part (so the open panel, not the summary, carries the answer). */
.mvi-part-summary:empty {
    display: none;
}

.mvi-part-summary .mvi-text,
.mvi-part-summary .mvi-math {
    display: inline;
    margin: 0;
}

.mvi-part-panel {
    padding-top: 0.25rem;
}

.mvi-choices {
    border: 0;
    margin: 0;
    padding: 0;
    min-width: 0;
}

.mvi-prompt {
    display: block;
    font-weight: 400;
    margin-bottom: 0.75rem;
    padding: 0;
}

/* The whole card is a <label>, so the entire row is the click/tap target. */
.mvi-choice {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    min-height: var(--mvi-target);
    border: 1px solid var(--mvi-border);
    border-radius: var(--mvi-radius);
    padding: 0.5rem 0.75rem;
    margin: 0.5rem 0;
    cursor: pointer;
}

.mvi-radio {
    width: 1.15rem;
    height: 1.15rem;
    flex: 0 0 auto;
}

.mvi-choice-content {
    flex: 1 1 auto;
}

.mvi-choice-mark {
    flex: 0 0 auto;
    width: 1.25rem;
    font-weight: 700;
    text-align: center;
}

.mvi-choice.is-correct {
    border-color: var(--mvi-correct-border);
    background: var(--mvi-correct-bg);
}

.mvi-choice.is-incorrect {
    border-color: var(--mvi-incorrect-border);
    background: var(--mvi-incorrect-bg);
}

.mvi-choice.is-correct .mvi-choice-mark::before {
    content: "\2713";
    color: var(--mvi-correct-fg);
}

.mvi-choice.is-incorrect .mvi-choice-mark::before {
    content: "\2717";
    color: var(--mvi-incorrect-fg);
}

/* ---- Fill in the blank ---- */

.mvi-fillblank-controls {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.5rem;
}

.mvi-input {
    min-height: var(--mvi-target);
    font-size: 1rem;
    padding: 0.35rem 0.6rem;
    border: 1px solid var(--mvi-border);
    border-radius: var(--mvi-radius);
    background: var(--mvi-bg);
    color: var(--mvi-fg);
    max-width: 12rem;
}

/* ---- Buttons ---- */

.mvi-check,
.mvi-next {
    min-height: var(--mvi-target);
    min-width: var(--mvi-target);
    padding: 0.5rem 1.1rem;
    font-size: 1rem;
    font-weight: 600;
    color: var(--mvi-accent-fg);
    background: var(--mvi-accent);
    border: 1px solid transparent;
    border-radius: var(--mvi-radius);
    cursor: pointer;
}

.mvi-check:hover,
.mvi-next:hover {
    filter: brightness(0.94);
}

.mvi-part-footer {
    margin-top: var(--mvi-space);
}

/* ---- Feedback ---- */

.mvi-feedback {
    margin-top: 0.75rem;
    padding: 0.75rem 1rem;
    border-left: 4px solid var(--mvi-neutral-border);
    border-radius: var(--mvi-radius);
}

.mvi-feedback.is-correct {
    border-color: var(--mvi-correct-border);
    background: var(--mvi-correct-bg);
    color: var(--mvi-correct-fg);
}

.mvi-feedback.is-incorrect {
    border-color: var(--mvi-incorrect-border);
    background: var(--mvi-incorrect-bg);
    color: var(--mvi-incorrect-fg);
}

.mvi-feedback.is-neutral {
    border-color: var(--mvi-neutral-border);
    background: var(--mvi-neutral-bg);
    color: var(--mvi-neutral-fg);
}

.mvi-feedback-status {
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    gap: 0.35rem 0.5rem;
    margin: 0;
}

.mvi-feedback-explanation {
    font-weight: 400;
}

.mvi-feedback-status .mvi-figure {
    flex: 1 1 100%;
    margin: 0.35rem 0 0;
}

.mvi-feedback-status .mvi-icon {
    font-size: 1.2rem;
    line-height: 1;
}

.mvi-show-solution {
    min-height: var(--mvi-target);
    min-width: var(--mvi-target);
    padding: 0.5rem 1.1rem;
    font-size: 1rem;
    font-weight: 600;
    color: var(--mvi-accent);
    background: transparent;
    border: 1px solid var(--mvi-accent);
    border-radius: var(--mvi-radius);
    cursor: pointer;
}

.mvi-show-solution:hover {
    background: color-mix(in srgb, var(--mvi-accent) 10%, transparent);
}

.mvi-show-solution:disabled {
    opacity: 0.55;
    cursor: default;
}

/* ---- Focus visibility (never removed) ---- */

a:focus-visible,
button:focus-visible,
input:focus-visible,
label:focus-visible,
.mvi-part-toggle:focus-visible,
.mvi-question-heading:focus-visible,
.mvi-part-heading:focus-visible,
.mvi-conclusion-heading:focus-visible {
    outline: 3px solid var(--mvi-focus);
    outline-offset: 2px;
    border-radius: 2px;
}

/* Headings/toggles receive programmatic focus on advance; keep an outline but
    no jump. */
.mvi-question-heading,
.mvi-part-heading,
.mvi-part-toggle,
.mvi-conclusion-heading {
    scroll-margin-top: 1rem;
}

/* ---- Small screens ---- */

@media (max-width: 30rem) {
    .mvi-fillblank-controls {
        align-items: stretch;
    }

    .mvi-input {
        max-width: 100%;
    }

    .mvi-check,
    .mvi-next,
    .mvi-show-solution {
        width: 100%;
    }

    .mvi-resources-list {
        flex-direction: column;
    }

    .mvi-resource-card {
        width: 100%;
    }

    .mvi-outline-chapter-summary {
        padding: 0.85rem 0.85rem;
        gap: 0.7rem;
    }

    .mvi-outline-chapter-number {
        width: 2.4rem;
        height: 2.4rem;
        font-size: 1.2rem;
    }

    .mvi-outline-chapter-label {
        font-size: 1.15rem;
    }

    .mvi-outline-chapter-body {
        padding: 0.75rem 0.7rem 0.9rem;
    }

    .mvi-outline-block,
    .mvi-outline-lessons > li {
        margin-left: 0;
    }
}

/* ---- Reduced motion ---- */

@media (prefers-reduced-motion: reduce) {
    .mvi-outline-chapter,
    .mvi-outline-topic,
    .mvi-outline-lesson,
    .mvi-outline-chevron,
    .mvi-outline-lesson-go {
        transition: none;
    }

    .mvi-outline-lesson:hover .mvi-outline-lesson-go {
        transform: none;
    }
}

/* ---- High-contrast / forced colors ---- */

@media (forced-colors: active) {
    .mvi-choice,
    .mvi-feedback,
    .mvi-question,
    .mvi-outline-chapter,
    .mvi-outline-topic,
    .mvi-outline-lesson--solo,
    .mvi-outline-lesson--nested {
        border: 1px solid CanvasText;
    }

    /* Color-drawn glyphs must keep a system color in forced-colors mode. */
    .mvi-outline-chevron {
        border-color: CanvasText;
    }

    .mvi-outline-chapter-number {
        border: 1px solid CanvasText;
    }

    .mvi-outline-lesson-icon {
        border-left-color: CanvasText;
    }

    .mvi-outline-topic-icon::before,
    .mvi-outline-topic-icon::after {
        border-color: CanvasText;
    }

    .mvi-outline-lesson-go {
        color: LinkText;
    }
}